Extracting sub image from a spectrogram

I have a time-series signal related to EEG recording. I would like to apply STFT on the signal then extract sub-image (I think some rows of the resultant matrix) that is related to a specific band, for example 4-14 Hz.

I am using the following code to apply STFT on the 1D signal x with the sampling freq. equal to 250 Hz.

win = hamming(64,'symmetric');
[ShortTFT, freq, tim] = stft(x, 250, 'Window',win, 'OverlapLength',50, 'FFTLength',250, 'Centered',true);

I need to know the first and last elements for the extraction process from the ShortTFT matrix.

Any help is appreciated.